The lighting device contains a lighting module comprising a light element series connection of at least two semiconductor light elements. Particularly the light elements series connection contains at least four, five or more semiconductor light elements. A drive circuit provides an output voltage and an output current at its output. The output voltage and the output current are supplied to the lighting module to provide electrical energy for lighting the light elements. In a preferred embodiment the semiconductor light elements are light emitting diodes (LEDs) or organic light emitting diodes (OLEDs). The lighting device according the present invention is particularly usable in outdoor applications, for example for illuminating streets, parks, gardens, boardwalks, cycleways or other public or private locations.
Such lighting devices are generally known. DE 10 2009 041 957 A1 discloses a device for operating LEDs. A cooling device is provided to actively cool the LEDs. A temperature sensor can be provided for measuring the temperature of the circuit board, on which the LEDs are mounted. The cooling device can be activated depending on the measured temperature.
US 2007/0108843 A1 discloses a series connected power supply for semiconductor-based vehicle lighting systems. The power supply includes a constant current source to supply current to the semiconductor light elements. For each semiconductor light element a bypass switch is provided. If the bypass switch is closed, the current flows through the bypass switch around the respective semiconductor light element. In so doing a failure of one single semiconductor light element does not affect the lighting of the other semiconductor light elements in the series connection. The bypass switches can also be used for modulating the brightness of the lighting device.